Field of the Invention
The invention relates to a remaining toner conveying apparatus provided in an image forming apparatus such as a printer, a copying machine, a facsimile machine, and the like.
Description of the Related Art
In an image forming apparatus, an electrostatic latent image is formed by exposing a surface of a photosensitive drum (image bearing member) uniformly charged by a charging device with laser beam corresponding to image information. After that, a developer (toner) is supplied to the electrostatic latent image formed on the surface of the photosensitive drum by the developing device to develop the electrostatic latent image as a toner image. Next, the toner image formed on the surface of the photosensitive drum is transferred onto a recording material such as a sheet by a transfer device.
At this time, all of the developer does not move from the surface of the photosensitive drum to the recording material by the transfer device, but some of the developer remains on the surface of the photosensitive drum. Such residual developer is recovered from the surface of the photosensitive drum by the cleaning device. Such a developer is referred to as a transfer residual toner, a remaining toner, or the like. Hereinafter, the developer remaining on the surface of the photosensitive drum after the transfer is referred to as remaining toner.
The remaining toner is recovered by the cleaning device and then stored in the remaining toner container provided in a drum cartridge. Alternatively, in general, the toner is temporarily stored in a remaining toner container and then conveyed into a remaining toner container different from the drum cartridge by a conveying portion such as a conveying screw to be stored.
In the configuration of the remaining toner container attached to the photosensitive drum, the remaining toner on the surface of the photosensitive drum is temporarily stored in a remaining toner containing portion adjacent to the photosensitive drum. Until the toner is discharged to the outside by the conveying portion provided inside the remaining toner containing portion, the remaining toner convects in the space formed between the photosensitive drum and the conveying portion due to the rotational force of the photosensitive drum.
Some of the developer contain abrasives for the purpose of actively scraping (polishing) the surface of the photosensitive drum. In the case of using such a developer, the remaining toner temporarily convecting due to the rotational force of the photosensitive drum in the space formed between the photosensitive drum and the conveying portion is in contact with the surface of the photosensitive drum and, thus, actively scrapes off the surface of the photosensitive drum.
The polishing of the surface of the photosensitive drum has the effect of suppressing the occurrence of image defect called image flow caused by electric discharge products adhered by an electric discharge phenomenon of a charging device. In order to electrically charge the surface of the photosensitive drum, the charging device is required to cause the electric discharge phenomenon in the vicinity of the charging device. It is known that, if such an electric discharge phenomenon occurs, the bonding state of the elements in the air changes, and an electric discharge product called NOx is generated.
If the electric discharge product absorbs moisture in such a state that the electric discharge product is adhered and accumulated on the surface of the photosensitive drum, the resistance of the surface of the photosensitive drum is lowered. If the surface of the photosensitive drum in a state of lowered resistance is irradiated with a laser beam, an electrostatic latent image is formed on the surface of the photosensitive drum. In this case, the boundary between the irradiated portion of the laser beam and the non-irradiated portion of the laser beam becomes ambiguous.
As a result, the electrostatic latent image becomes blurred. This phenomenon is called image flow. In order to suppress the occurrence of such image flow, it is necessary to increase the convection performance of the remaining toner in the vicinity of the opening of the remaining toner container facing the surface of the photosensitive drum and to polish the surface of the photosensitive drum by using an abrasive containing in the remaining toner.
JP 2015-028509 discloses prevention of image flow and recovery operation. JP 2015-028509 discloses a technique of detecting a density detection pattern formed on the surface of the photosensitive drum by a density sensor and polishing the surface of the photosensitive drum by an idling rotation operation or the like based on a change in density. In the idling rotation operation of JP 2015-028509, the polishing effect for the surface of the photosensitive drum by the cleaning blade is expressed.
In addition, in some cases, if the convection performance of the remaining toner in the vicinity of the opening of the remaining toner container facing the surface of the photosensitive drum is poor, paper dust contained in the remaining toner is separated in the vicinity of the remaining toner containing portion, and a paper dust layer (hereinafter, referred to as a “paper dust net”) may be formed where paper dust is laminated in the vicinity of the opening. In some cases, such a paper dust net is sandwiched between a cleaning blade and the surface of the photosensitive drum, and thus, cleaning defect may occur. The occurrence of the paper dust net is suppressed by the increase in the convection performance of the remaining toner in the vicinity of the opening of the remaining toner container facing the surface of the photosensitive drum.
However, in the remaining toner conveying apparatus disclosed in JP 2015-028509, if a conveying speed is slowed in order to improve the convection performance of the remaining toner, the remaining toner is clogged in the vicinity of the discharge portion of the remaining toner. In addition, the rotation of a conveying member is hindered, and thus, there is a problem in that the conveying member is damaged.